The most frequently occurring types of voice disorders are those that are related to vocal abuse and/or misuse, i.e., "vocal hyperfunction". However, there is a paucity of hard data concerning: 1) specific physiologic and acoustic manifestations of vocal hyperfunction, and 2) the actual role of hyperfunction in the development and maintenance of voice disorders. Thus, the major goal of this project is to further develop and use quantitative measures of voice production to provide objective descriptions of conditions referred to as vocal hyperfunction. This work will involve the use of non-invasive, indirect measures of glottal air flow, transglottal air pressure, relative vocal fold contact area (EGG), respiratory function, and a number of derived measures to study both organic (nodules, polyps, contact ulcers) and non-organic (functional dysphonia/aphonia) manifestations of vocal hyperfunction. These measures will be examined in relation to encoded descriptions of the pathophysiologic status of the larynx (from videolaryngoscopy/stroboscopy), pertinent medical and psychosocial factors and perceptual characteristics of the voice. Interpretation of results will be added through use of a simple model of vocal-fold vibration. The overall design of this project continues to be based on a set of interrelated hypotheses which form a descriptive framework for vocal hyperfunction. The framework holds that there are different types and stages of hyperfunctionally-related voice disorders. Data analysis and interpretation will continue to be related to this framework. The proposed work will build on previous efforts by focusing on a number of specific investigations related to hyperfunctional and normal voice production including: group-based studies of different types of hyperfunctional voice disorders, "vocal stress testing", efficacy of behaviorally-based voice therapy, and studies of normal inter- and intra-subject variation associated with measures of vocal function. The information gained from these efforts should lead to new insights concerning the etiology of vocal hyperfunction, and to improvements in clinical methods used to diagnosis and treat these disorders.